We can, thus, observe several types of variability, often present at the same time. Among A-F pulsating stars, we can find high-order \(g\) -mode \(\gamma \)  Doradus (GDOR) type pulsations with periods in the order of hours to days [1]}, [2]} generated by the convective-flux blocking mechanism [3]}, [4]}, \(\delta \)  Scuti (DSCT) low-radial order \(p\) -mode pulsators [5]} with pulsations excited by the opacity mechanism in the He ii layer [6]}, [5]} and by turbulent pressure [8]}, [9]} with periods of hours. There are also hybrid stars showing both DSCT and GDOR pulsations [10]}, [11]}, [12]}, [13]}. SX Phe stars, which are Population II stars, have similar pulsational characteristics to DSCTs, which belong to Population I stars [14]}. Another type of pulsation appearing among A-F chemically peculiar stars with strong magnetic fields are p-mode oscillations with periods in the order of minutes observed in rapidly oscillating (roAp) stars [15]}. GDOR, DSCT and roAp stars observed by TESS in sectors 1 and 2 were thoroughly studied by [16]}, [17]}.
